is there an easier way of doing corners like this?
Here's a pretty solid workflow if you don't desire to use multiple objects in the creation.

I'm posting the image sequence for now, so I don't mess that part up, then coming back to give the commentary per image.


Shift+A >> Mesh >> Plane.





Tab to enter edit mode.





I to inset the active face the desired amount.





Delete >> Only Faces.





Result of Deleting the face (giving you the major frame profile).





A to select all faces.





E to extrude the desired overall frame thickness.





Ctrl+R >> 2 >> LeftMouseButton >> RightMouseButton





Click on the Face Mode icon/button.





Z >> Select the inner ring of faces (as shown).





With your cursor just outside the outer edge of the frame E >> S >> Move your mouse toward the center of the frame the desired amount >> LeftMouseButton





Click on the Edge Mode icon/button.





Select the Edge Loops at both the Inner Top &amp; Inner Bottom of the frame.





Ctrl+B >> Move your mouse outward the desired amount >> Either type the number of segments &amp; hit Enter OR scroll up on the scroll wheel of your mouse the desired amount &amp; LeftMouseButton.





Hit Tab &amp; you are complete if you desire a 4-Sided frame.





If your desire is to have a 3-Sided frame >> Tab to enter edit mode. >> C >> Select the bottom most horizontal edges of the frame.





Delete >> Only Edges &amp; Faces.





The result is two empty holes that we must repair/fill.





Loop Select the left most hole. >> F to fill.





Loop Select the right most hole. >> F to fill.





Select both Edge Loops again.





S >> Y >> Numpad 0.